1. Field of the Invention
The present invention relates generally to the field of generating databases and more particularly relates to a system and method for generating a digitized matrix database in accordance with a paper map source.
2. Related Art
Database generator systems and methods are used in many applications. Generally, the database product of the database generator system is used by application computer programs in performing the tasks required of the application program. One application utilizing a digitized database is a visual display system providing information to a user where such information is based directly from the digitized database or is based on processing of the digitized database.
Databases having separate selectable features are prepared using data obtained from numerous sources. For example, digitized map databases are prepared from sources such as satellite information, paper maps, aerial photographs and the like. Such sources can be used in several combinations and with various methods to produce a digitized database meeting the specific requirements for that particular database. Each type of source provides certain qualities that can be used in generating a digitized map database. However, each type of source also has limitations which may not meet the requirements for some databases.
Although satellite scanning provides data immediately in digital format, this method does not provide all the features which can be extracted from a paper map. Also, the resolution of the data obtained from the satellite scanning is limited.
Various digitized information can be obtained from aerial photographs. For example, using stereoplotters elevation data can be extracted. However, using aerial photographs to extract other topographical features requires manual digitizing methods.
Manual digitizing methods exist using aerial photographs or paper maps as the source for the database. The database is created by first drawing grid lines on the map or aerial photograph at intervals representing the desired resolution. The next step is the manual coding of each grid intersection using a digitizing tablet. The third step is to process the resulting data to obtain the database format required.
The disadvantages to the manual digitizing method are several, including: (1) a significant number of errors can be expected due to the number of manhours required to perform the tedious task of manually digitizing the vast amount of data and then verifying the results; (2) a high cost can be expected due to the large number of manhours required to implement this method; and (3) the resolution of this method is low, typically 100 to 500 meters per data point due to the length of time required to perform the task. An increase in the resolution under the manual method is directly proportional to the increase in the number of manhours required to complete the task. It can be seen that eliminating one disadvantage under the manual digitizing method increases the detrimental effects of the other disadvantages.
The Defense Mapping Agency (DMA) provides mapping, charting and geodetic support and services to the United States Department of Defense through the production and worldwise distribution of maps, charts, precise positioning data and digital data for strategic and tactical military operations and weapons systems. DMA has several digital database products that are described in a paper entitled "Defense Mapping Agency (DMA) Policy for Digital Mapping, Charting and Geodesy (MC&G) Support of Advanced Systems" by Barry D. Shelkin, which was presented at the Sixth Interservice/Industry Training Equipment Conference in Washington, DC in October 1984, which paper is incorporated by reference herein. Although DMA provides digital terrain elevation data and terrain contour matching data in matrix format, and other digital data in vector format, the rapid expansion of requirements for digital MC&G products to support advanced weapon systems has required DMA to reevaluate its digital data policy. The new DMA policy as represented in Shelkin's paper provides for a standardization of the methodology used by DMA in producing its digital MC&G products.
The United States Army is now using a training device known as Army Training Battle Simulation System (ARTBASS). ARTBASS is designed to provide battalion commanders and their staffs with realistic training in developing, assessing and correlating tactical and logistic data which was previously only possible through the generation of large scale field exercises or in paper dominated command post exercises. A typical ARTBASS device contains two color monitors on which topographical features are displayed in place of paper maps. The digitized map database representing the topographical paper map used for ARTBASS was originally obtained from DMA. The digitized map database utilized by ARTBASS had a required resolution of a 25 meter square. To produce such a digitized database, DMA had to use special methods to produce a digitized map database at the required resolution and with all features stored in one file. Additional processing by the user was required to display individual map features such as vegetation. As indicated in Shelkin's paper, DMA now has standardized its methods for all users; and such methods do not provide directly a digitized map database having such resolution and feature characteristics as required in ARTBASS.
There are two formats for digitized databases relating to application programs using digital displays. One format is known as the vector format, where the informaion stored contains a starting point with a direction and a rate. Not all points on a display have vector information stored in the database. To obtain the current status of a point on a display, the application program must constantly follow all vectors in the database to determine which vectors cross such point.
The other format for digitized databases is the matrix format. In the matrix format each data point on the display has the information in the database associated with that point. Unlike the vector format, the current status of any point is known instantaneously when the database is in matrix format.
The advantage of using a database having a vector format is that it takes less time and space to generate the database. The disadvantage is that the application program uses more time to process the vector formatted database. In a real-time simulation system such as ARTBASS, processing time is critical to meet the real-time training requirements. A digitized database in matrix format requires less application processing time, therefore, the matrix formatted database is better suited to meet the timing requirements. While the database using matrix format requires more time to generate, the processing time for the application program is significantly less because the information is available in the database.
ARTBASS represents one application of digitized database requiring a database generator system and method that will produce a digitized database in matrix format with a high resolution. Other applications of such digitized databases are anticipated because of the ever increasing utilization of computers in all phases of decision making processes. Such applications include low altitude navigation and avoidance, mapping of the ocean bottom for underwater navigation, emergency management systems, warning systems, and the like.